Phone blocked

I joined mtn about a year a go and from day 1 it's been problems. For a whole year now I have been charged more than what I signed up for and ever time I phone in or chat to their customers center online they tell me they will have it sorted out. But it never happens! Now today they blocked my phone because I did not pay way more than double my contract. When I tried phoning in to sort it out their call center is closed. I decided to turn to hello peter and Facebook to help since I don't get help from mtn themselves to help sort this problem out.