Non-performance of letting agents

We employed VIP properties to be our letting agents for one of our properties in Pretoria. Due to the constant bad service we have received from them, we wrote them an email in November informing them that when the lease agreement expired at the end of January 2015, we will not be renewing it and that their services will thus be terminated. I got a call from the agent on the 29th of January telling me that the tenants were at her office requesting an extra month, to which I declined informing her that we were not interested in extending the lease agreement or allowing the tenants to stay on. <br> I tried calling her a number of times from the 3rd of February to arrange for the collection of keys but she did not answer nor did she call me back. When we went to the property on 7th of February we found that there were people still staying there. They said that they went to V.I.P Properties on the 29th of January and were told by Zarine, after she called me, that the owners of the property said they could stay on as long as they paid their rent on or before the 3rd of every month instead of after the 7th.<br> We spoke to the principal but VIP Properties have not sorted the matter out till now.