Duration Windows

I am a long standing trade customer of Duration Windows, my company is called Deen Builders. I have had minor issues with orders over the years which in fairness to them Duration have always resolved but the most recent order has opened my eyes to what a truly terrible company they are. The order for secondary glazing was signed off by myself correctly but once we got on site to fit the order we realised that Duration had made 2 of the units from the wrong profile and 1 was completely the wrong size. Duration admitted the error (without any apology) and said they would fast track the replacements which ended up being 4 weeks. This is 4 weeks on top of the 7 weeks my customer had already waited and of course I can't be paid until the job is finished to the customers satisfaction. This sloppy production error by Duration obviously required me having to send a fitter back for another day which I duly sent them an invoice for once the job was finally completed. Today I heard back from Duration via email who told me that they do not pay compensation or labour and that this is stated on the order confirmation. They also say that they ask us not to book installations until the goods are to our satisfaction. These terms and conditions are frankly ridiculous and I am fairly confident would not stand up in court if a claim was made against them because they have supplied goods that are not as described and have caused their customer additional labour costs. Reading through some of the other negative reviews I am not surprised by the treatment I received. This will be the last time I use Duration and I would urge all contractors thinking of using them to think again because if they mess the order up the costs are all down to you!