Unacceptable/no Service

ISP MWeb persuaded me to move my ADSL to them to have 1 support entity. I simultaneously upgraded speed from 2 to 4Mbps. Had nothing but problems with download speed ever since. 9/10 speed between 0.2&1.0: 1/20- 1/4 of what they contracted. Although OCCASIONALLY been an acceptable speed often between 0.01&0.05=unusable. Reported to MWeb & written emails Ref***. Although they contacted me by telephone & email, has now carried on for 7 months without resolve! They are doing EXACTLY what they undertook not to do - passed blame on to Telkom & say there is nothing further they can do. Say it is congestion problem & I need to wait a few (MORE) months until Telkom have fixed! Complete nonsense: how can there be congestion at 1:30 in the morning and similar times? \Service"is same at all times of day - not indicative of congestion. They continue to charge me for 4Mbps service - that is theft. An internet connection is absolutely essential to me & there are 3 others in the family that also require. I effectively have no service at the provided speed. I cannot & am not prepared to wait a few more months + I want a refund of all that I have paid towards a service that was not received."""