Not taking responsibility for mistake

I ordered kitchen cupboards from Lansdowne Boards. Upon delivery I saw that 2 backing boards were cut skew and the counter tops were 3mm short. They exchanged the boards but refused to accept responsibility for the incorrect length of counter top. They then tried to blame me for the wrong measurement. I only gave them the length of the wall and the type of counters I wanted. Their sales person drew up the sketch with measurements. On the phone the sales person named Edries then fabricated a story about me asking for longer tops - even though the counter tops are 10mm short! If you are making the cupboard carcasses how do you cut the top short?<br> This is not logical.<br> <br> I demand a response and a replacement counter top.<br> Pathetic customer service