Unusable ADSL Speed

I subscribed to FNB Connect's Uncapped ADSL Service last month. First few days were fine, until beginning of March. I sent a mail to FNB Connect early on 5 March, giving them my speedtest results (1010ms ping times, with 0.3Mbps download speeds on a 4Mbps service), at the same time I used a 1GB Capped Axxess account to test, I got ping times of 40ms, and 3.6Mbps Download speeds, same line, same time. I then got a test account from FNB, with the same results. I was told they logged the fault on the 6th of March, with no feedback since. I had to switch ISP's to be able to use my line, as I could not work on this service at all. I cancelled this on Friday, after waiting a week for feedback, with no assistance. FNB is refusing to give me a refund for this service, because on the logs they can see I accessed it up to 6 March. I find this unacceptable, as I was forced to use another provider, it was not out of choice. I have to work from home, and could not do my job as a result of unusable speeds from FNB Connect.