Breach of Agreement- Vodacom Advertising

We were approched by a marketing company (S&N Cellular) representing vodacom in October 2019, to use the exterior boundary of wall for advertising purposes. This is a prime location as it's metres away from a busy highway. After discussions, it was agreed that the wall will be painted with a Vodacom advert for a period of 12 months. The fee discussed was R1000 a month and thereafter the wall will be returned to it's original colour if there was no new agreement.

It's been 2 years and wall still remains as it is. We are unable to get a hold of anyone from this associated marketing company. We have only been paid for the first 2 or 3 months. I would appreciate it if vodacom would assist immediately and deal with us directly.