Poor Poor service

Ive been a nashuamobile customer for more than 10 years,i have 3 Mtn cellnrs on my contract which obviously means im a mtn client.I have never missed a payment and have allways been a loyal client.one of my numbers was due to upgrade in May.I went to a Mtn branch and they said i can upgrade however they did not want to upgrade me nobody has bothered to phone me back.Ive sent numerous emails and even app**** online yet nobody has the decency to contact me.poor pathetic service for a client thats been with mtn for more than 10 years.i want this to be sorted otherwise ill cancel all my contracts.Ive never missed a payment not once so pls someone assist and do my upgrade.10 years a mtn customer and now this