Planting grass seed in zone 5 & 6 now is a waste of time, money and effort....the soil's temperature is too low to ever think the seed will germinate in time and hold sufficient temperature to allow the grass to gain strength.
Much better to think spring for this fix.

What caused the damage in the first place? Weeds are a fact of life and should be kept after on a regular basis---not allowed to gain strength by avoidance.
It sounds like spot treating is not going to do the job....an overall spraying should be considered.
(some jurisdictions have a law against spraying--relying on the professionals to do it in an acceptable way)
Weeds are best treated when they are growing their best....so that speaks for mid spring and summer.
Other than spot spraying directly and digging out the weed I cant see spraying at this time is of any use.

I don't know how they might treat your complaint but if they know you are not going continue with their services they might not feel the need to try to please you.....so ...stay mum...let them do what they can...then inform them they have lost you as a customer.

Seeding is still being done around here, for patching mostly. I volunteer at Extension as a Master Gardener and we are advising people that the window is closing.

We do not keep after weeds on a regular basis. We treat fall germinating weeds in the fall and spring germinating weeds in the spring. Dandelions, henbit and other broadleaf weeds, including large patches of clover, respond well to weed killers at this time of year. In fact, spraying on a cool morning when the temperatures will be up into the 60s and 70s in the afternoon is the best way to maximize the effectiveness of these herbicides.

We only spot treat. We never see the need to do broadcast spraying. Why would we spray chemical on large areas of turf that are relatively weed free??

The damage was caused by overapplying the herbicide -- or he mixed too strong a concentration. My guess is he oversaturated, and I know from experience that can kill the grass along with the weeds. That's why I began using a pro to do the job, and the man who worked for the company previously always did an excellent job. The guy who did this job is a licensed pesticide applicator, and FYI, jurisdictions that require a professional to spray weeds do not prevent homeowners from spraying their own weeds.

I have no intention on telling him he's fired -- not yet. My question has to do with whether or not to pay the bill.

Hi, sorry to hear that. I had a national company do that to my parents yard. In fact the day we came home from my dads funeral planning, Tru-Green and had applied fertilizer and Barricade in the heat wave of 2012. that smoked the lawn and I fired them.

I would not pay the bill.

Think of it this way... suppose you hired a painter to paint your living room. He rolled the walls just fine, but got green wall paint onto the trim, and got white trim paint onto the walls. And to make matters worse, he put a big scratch in the sheetrock with his ladder at one point. It's a big mess & you're going to have to fix it yourself (your time costs money) or you're going to have to pay another painter to come in and re-do it (PLUS fix the drywall!).

Now... would you pay the original painter?

The real question is... would you trust this painter to come BACK into your house and fix the drywall? No. And don't let these idiots back into your yard. If he can't mix some trimec I certainly don't want him operating a verticutter in your yard?

Sheesh... Imagine if he had some prodiamine in the mix or something... you won't have grass next spring either!

I certainly appreciate you wanting to be fair. But you're paying for a service. I work in a service industry (unrelated to lawn care). In my business, we perform our task 100%, or the customer doesn't pay. The parent company is a Fortune 500 company... and a single (substantiated) customer complaint is enough to put my next promotion in jeopardy. And a failure that causes customer property damage--it's company policy that I be terminated in such a circumstance.

You paid them to fertilize & weed-treat. The goal was obviously a healthy & (relatively) weed-free lawn. It sounds to me like you have neither. Thus the service was not performed. Don't pay the bill.

And do the national company a favor. Call them again & let them know that their franchisee is giving their national brand a bad name. The company I work for has been known to decide not to renew franchise agreements for that sort of thing.

My $0.02.