Mweb ISP disgrace

Mweb's internet wifi connection is unstable.. Unreliable slow... Or completely down. After lodging 3 complaints reporting very slow or no intermet connection. Working from home with slow or no internet connection.. I has to formally request tolo cancel.. They rep**** on an email that I need to pay a penalty fee. How do you charge a client a penalty fee if they have valid complaints and reports a valid reason. I am being charged for a service that has not been delivered and I cannot cancel or be realsed if I don't pay a penalty fee. This is unacceptable