Contract cancelled without my consent

I had a problem with my decoder, to it to multi choice centre and was told i needed a new explora, so i bought a new one and called the DSTV call centre for them to connect the new decoder to my account, to find that my contract that i had renewed was cancelled without my knowledge, now they have additional changes that i have to pay for the mistake that they made, i just wanted to relink the new decoder to my old account, which is not what happened, who instructed them to cancel my contract without my concern, I was paying R439 on my contract, but now they have added charges for me to pay R607.33 which is not correct, i need this fixed ASAP