Funds missing from QB Checking from invoice paid by client using the invoice link 6 weeks ago. QB support is useless.

I received a notification that a client paid an invoice 6 weeks ago but the money has yet to show up in QB checking account. I have spent over 40 hours on the phone with support but they are useless. I think my only option at this poling is to file a complaint or take legal action. I have screenshots from the client showing the payment has cleared. What else can be done?