The house I was buying had been advertised through Chancellors as well as another agent. I bought through the other agent.
Having moved in I went out to the shops one day and arrived home to find one of Chancellor's agents in my lounge showing prospective buyers round. I pointed out that i had already bought it and asked for the keys. I was informed I hadn't bought it through them and as far as they were concerned it was still for sale. I took the keys off him and threw him out then went and replaced all the locks.
The people who sold the property to me had repeatedly phoned and written to them asking them to remove it from their list. They had also requested the return of historic documents for the property which have never been found.
Two weeks later I walked past their window to find my house still being advertised for sale. Marched into their window, removed the photo, removed all the sale details from the rack and gave them merry hell. No apology, not even an acknowledgement that they were in the wrong, they just stood there and looked at me.
A couple of years later a neighbour emigrated and put their property with them to rent. I was constantly finding the front door left wide open and the back door left unlocked. Nobody was interested.
I wouldn't use these people if they were the last agent on earth!