To address the OP's point, yes, getting through on the phone is next to impossible at the moment, but (without making excuses) there are a number of reasons, mostly not to do with Wickes. Travis Perkins (same group as Wickes) have taken the decision to only supply products to infrastructure, transport and customers who service the homes of vulnerable people. This is a decision taken to allow employees and customers to be kept safe by a) barring customers from physically coming into branches and b) running a light supply chain (social distancing in a Primary Distribution Hub is beyond challenging).
This means that all the usual tradesmen can't get their materials from there and are going to Wickes instead because a) the company pointed them there rather than to a competitor and b) they carry the same/similar ranges of basic building materials. Buuut, that means 1000 ish TP branches' customers are trying to get stuff from 300 ish Wickes branches, alongside all the DIY'ists like me who are stuck at home with nothing else to do. To say its challenging would be a gross understatement and as always in times of such high demand, people have been moved from answering customer service calls to taking sales calls. If you think that's putting profit before customer service, that's your prerogative, personally, I'm glad the company is doing what it can to make sure that 28,000 people get paid next month, as its considerably more than some retailers are managing in the current climate. My advice would be to email them, it will get corrected, in time, assuming you aren't hanging on for that £9.55p
On the subject of delivery. Wickes operate a hub system where certain stores fulfil bulky deliveries for a whole area, eg. where I am (Solihull) I get stuff from either Coventry or Hinkley. These normally hold 14 days of stock, but at the moment that isn't the case for obvious reasons.
I recently had 900kg of oak sleepers delivered (1800mm long), the supplier sent them on a pallet. I felt so sorry for the guy that I handballed them off in the end as it was just dangerous trying to get them on the tail lift using a pump truck. Thankfully the guy could afford to wait the 20mins it took me. I imagine many people would have to have got done quicker than that