Cannot receive calls from Cell C or FNB networks- number doesnot exist

I have ported from FNB to MTN just under a year ago and cannot receive any calls from Cell C or FNB networks. When subscribers from these networks try to call me they get "the number you have dialed does not exist" but I can call them without any issue.

I have tried calling numerous times. MTN passses the blame to Cell C/ FNB and they say I should take it up with MTN. I am an MTN customer and so expect some assistance from MTN. As far as my research goes, the routing tables need to be updated.

Please can you assist my number is ********** 060