INCORRECT ALLOCATION AND MISSING DATA

Hi. So it's been 4 weeks now since my data were ****** by mtn. i took a 24 months contract with mtn in 2019 i.e 40gig anytime and 40gig night. But since november 2020, mtn decided to allocate 30/30gig instead of 40/40gig as per the contract. So i have been calling the 135 number and always when i call this number, they would give me a new reference number and be told that my case will be investigated. I'm tired of calling and be told one thing. i don't think i will renew my contract come 2021 with mtn because they have failed me, if possible i will terminate this nonsense contract with mtn.