Finishing Touch Windows

Work was undertaken at one of my rental properties. The contractor was arranged by the tenant. When the contractor made contact with the landlord, they were asked to submit a digital copy of their public liability insurance, which they failed to do. They only showed a copy face to face but failed to send it via email for the landlord to keep/check!
Also, a 50% deposit was taken from the customer in advance, and did not make contact for a further three weeks! This was very inconvenient for the customer who had to keep chasing them. Ideally, it would have been a lot better had the job been completed and full payment was taken together.