If you have a pump for a basement bathroom, then it is an "ejector pump" for effluent. "Sump pump" is strictly water that does not need to be directed to the septic tank or city sewer and resides in a different kind of pit.

If you are sure it is the performance of the ejector pump, and not the toilet itself or any power issues, then call a plumber. Actually you should probably call a plumber no matter.