Forward calls from MTN sim to TELKOM Sim

After I've gotten a call from a sales person named Jonathan, my forward calling from my MTN sim card to my TELKOM sim card is no longer working. I have lost so many important calls because I have had this MTN number for almost 20 years.

I've called 135 about 10 times to restore my forward calling but to no avail.

PLEASE SORT IT OUT AS MANY PEOPLE CANT GET HOLD OF ME