After 5 years of good relationship with some people there, you cannot trust them!!! It's all about the money in Poland!
It is the socialist mentality. I recently had a situation of having a rental flat partially repainted, my father in law decided he wanted to give some work to a local builder/jack of all trades from the countryside that oversees his countryside house. I agreed and allowed him to arrange details, the chap turns up and gives a quote and they agree PLN 8 per m2 exclusive of paint, but inclusive of two coats preparing ,filling and moving furniture.
Two weeks later they turned up to do the job, he had quoted my F.I.L, PLN 1,700 as a finished price, at the end of the job they asked my F.I.L for PLN 2,100, because the job had taken longer than expected. I met them for the first time on the last day, when I turned up to inspect there was a heated argument going on between the three of them, I actually thought my F.I.L was going to have a heart attack, he is 72 years old, after listening to both sides of the argument, I informed them all that I understood the situation and now we should pay, but before doing so I need your invoice for PLN 2,100 inclusive of VAT. Both men looked at with with shock in their eyes and informed me they did not have the invoice with them, at this point I informed them I would be in the countryside closing down the house for the winter with my F.I.L at the weekend and I would pay them when I had a VAT invoice, which is standard practice in Poland. On the saturday we arrived in the countryside and went about our normal routine at the house, after 30 mins the wife of one of the men came over and asked my F.I.L to come over for a cup of tea, after about an hour he returned with a smile on his face with a slight smell of vodka to his breath and told me all had been settled. I did not get involved they are all happy and life goes on, the Polish way.