Just a warning to trades people working for this c...

Just a warning to trades people working for this company. I did work for them and because they didn t offer a purchase order ( which they never had given in past jobs) they would not pay me! I have in writing from them admitting fault and that they know the work was completed yet would not pay me! After 6 months and repeated tries l have told them basically not to both and l concede to just a bad experience. Poor form!!!