Builders customer service failure

Placed order online for some drainage grating, searched for availability and during process made a mistake during checkout and selected delivery. After payment on confirmation email I noticed mistake and called contact centre to ask for it to be changed to collection. Spoke to 2 consultants who escalated to store and promised feedback. This was on Thursday. On Saturday I was in store and asked if I could collect as I asked for change to happen but received no confirmation but staff in store ” can't help we have not seen change and set for delivery ". Frustrated I left. Today I finally got a call again from contact centre asking if store contacted me , which hasn't happened. Explained above to agent but they cannot do anything or even confirm delivery will still go ahead. Agent subsequently returned call 20min later to confirm delivery. Completely frustrating and idiotic process , definitely not customer focussed.