Unhelpful Call Centre Agent Regarding Upgrading of a Contract

I have been a very loyal Cell C customer for years and I have always had a very pleasant experience when dealing with any of their call center agents, as well as their staff in their various shops. However I recently contacted the upgrades department was was "helped"by a most unhelpful person who seemed unwilling to listen to me or help me.

My upgrade date is on the 30th of this month and I have unfortunately started experiencing problems with the microphone on my device and it is now affecting my job, as I am unable to make or receive phone calls as I used to be. The person on the phone told me that I am able to upgrade, but only if I do it over the phone. Unfortunately I have had bad experiences in the past with this and prefer to upgrade in person at a shop with someone who is able and willing to help me while I am there. The agent didn't even bother to listen to me when I suggested this, immediately shutting me down and not wanting to discuss the matter saying that I have absolutely no choice, but to go through her for my upgrade.

This is very disappointing, especially since my account is paid in advance and I am always in credit with your company. Please can I have someone call me who is able and willing to address my situation.

Thanks