MTN 2 Systems lost my number

MTN is making a two-system problem mine. So in August last year, my mom passed, and I transferred my sister's number to my account. 2 weeks ago the number just stopped working, after 7 ticket numbers and 10+ phone calls, apparently what happened is that my mom's account is on the "old" system and I am on the "new" system. When they closed her account they closed this number also. I know had to prove it was transferred, even though it was done by my MTN, after providing proof, now MTN legal apparently has to discuss what's next. I have to phone twice a day otherwise nothing happends :(