Having read this thread I'm just glad that I did my buying a while ago. I do have the highest regard for Screwfix even though I have had my share of problems. To respond specifically to one of the points raised, true, they did use to advertise Next Day Delivery but they now state at the point of checkout that you might not get next day. Also I think that they may put in a time/date factor now (after I moaned long and hard and complained to Trading Standards) since if you placed an order on Thursday very close to the 6pm watershed then you proabably would not get your goods until Monday and their system was not sufficiently smart to ask if you wanted to pay a bit extra to get it there on saturday.
Again, most times, I get the stuff next day and so I can't really complain. I think their Customer Service is first rate.
What I think may have happened is that their IT systems got overloaded with the back orders as, of course will their email and phone system. It's not rocket science to work out what is happening up there then. The longer the delays, the more people will be ringing to complain or sending emails to be answered ..and because we expect a fast response, we complain again and again because we can't get through on the phone..and then when we do we spend the first several minutes moaning at the porr Customer servcie rep..which just adds to their workload...which pulls people off of doing what they'd like to do which is ship stuff...but then they haven't got the staff yet ! Or did they just make the cardinal sin of installing a new computer system at the same time?