Letting agent supplying contractors?

As a single property landlord who lives a fair distance from my property. I am heavily reliant on the letting agent to find suitable contractors for jobs at my property.

A prime example involved a staircase handrail, which was to be moved to the opposite side of the stairs and repainted. The letting agent informed me that the work had been completed and that the contractor had been paid.

I was due to pass near the property, which coincided with a planned property check by the letting agent and the tenants agreed for me to attend.

Looking round, it was obvious that the work had not been carried out. I took numerous photos, and the letting agent was profusely sorry, but she did not work in that office and was only covering.

It took months to get the money back from the letting agent, and I told them that the contractor was banned from my property.

It seemed to me that there is no oversight on the contractors, and one has to trust them when they inform the letting agent what work needs to be done and that the work has been carried out.

What degree, if any, of oversight is there regarding the amount contractors claim and whether the work is carried out to a high standard?

Thanks,

Tom