Bad service

I have 3 contracts with MTN, 2 mobile phones and 1 SIM for data. The past 2 months my data seems to be depleted way before it gets loaded on the 12th. I have this SIM for more then 2 years and it never depleted before it loaded again. I always had data left way before it got loaded. Since I took out a contract 2 months ago this has been happening. When I enquire in store they tell me many customers are complaining about it. I think I would rather just cancel that contract and look elsewhere.