Incorrect length slats

I have received extremely bad service from this company. In November 2018 I ordered vertical blinds with specific length slats. When I picked them up from Builders - Alberton and got home I noticed that the slats were 50 mm shorter than ordered. I contacted them immediately to report the matter and they promised to replace them with the correct length as ordered. To date they still have not replaced them. I have been in contact with them and they are always so rude and have every excuse imaginable, they don't even respond to my emails. Absolutely disgusting service!!!