Ongoing Broadband Contract and service Issues

Hi. So back in March i renewed my contract (regrettably) for just broadband. Since then we have had 5+ call outs with technicians, all wires from the cab to house replaced and still experiencing issues. However. That is the last issue on the list, i’ve just requested my SAR information as i’ve reached my wits end of being constantly lied to by customer service. 

When i renewed they moved us onto a 500mb package for £37 for 18months, which i was ok with. The received my first bill for £40 and no sign of the rolling £3 credit i was promised on the phone. When i spoke/web chat with someone i was then promised 1gb for the same price of £37, and they changed my contract to 24months although it was explicit that i agreed to 18months, they told me multiple times this would be fixed, and ofcourse it never has been. I then get a new bill today saying i owe £16.01 that was not paid in my last bill!!! Again i was told by two different agents last month that i was due to pay the discounted £23.99 as they were crediting. my account due to all the hassle and the poor service we are receiving. 

I’ll be honest i’m not sure where to go with this as it’s been stressful to say the least and all stemming from a poor service we are receiving, i can’t deal with just constantly agents saying they are going to fix something to get you off the phone and not following through. What’s the legal stand point on this, as i feel Virgin have breached the contract several times. Any help and advice on this would be appreciated? Thanks