Paid early but still getting a bad service-MFC

Pleased tell me why do I get calls for "not paying my installment ".

Kindly train your employees to perform their duties on time as I have sent the proof of payment last week already. The guy who just called me now he doesn't show willingness to assist all he does is to force me to redo what I've already done regardless of the current situation.

I need someone to sort this out today please