Incorrect data being loaded on contract !

Mtn is full of nonsense guys. I signed up for a 40GB including a router deal which was advertised on TV which they deduct R240 a month for. All of a sudden in the month of August,12th they gave me 20GB of data, half what was advertised, agreed and signed on. Ive been calling them and they keep logging inquiries which keep not getting resolved. When calling them they state I should send the policy documents as if the deal I took up does not exist ?! they can simply check their systems and see how much data they’ve been giving me monthly now it’s suddenly changed and how much I am paying for it. now I just spoke to Luyanda who now advises the full 40GB was loaded, where else the previous consultants advised that they do see on their side the incorrect amount of data was loaded but just not rectified yet - when asking for the proof that the full 40GB was loaded on the 12th, I have to now send a letter on a pdf requesting for it... stalling techniques. I took this 40gigs deal because I need it, for work and school - It’s like you sign up for the service but cannot enjoy it in peace. Now I’m having to buy prepaid data because MTN couldn’t adhere to their own deal and policies. I’ve got about 5 different reference numbers for the same query and countless phone calls to MTN and still nothing is sorted out.