Large B&Q order - made in October but still not received

Hi

As the title states, I made a large order in October and I'm yet to receive it. Here are the details:

I bought 280 carpet tiles in the 3 for 2 offer - saving almost £400 off the regular price!

I ordered on the 26th October 2019

I ordered in store for home delivery

I paid in full on my credit card on the order date

When I check with the store, they say that it's a stock issue with the manufacturer, that they don't have enough material to complete the order (presumably not just mine) following a lot of orders in the 3 for 2 offer. Apart from my enquiries, I've not heard from B&Q at all which I think is pretty poor.

My question is : Is it reasonable for me to ask for a discount due to the delay and possibly for poor communication too?

I'm just worried if I do ask for a discount, they may cancel the order when I still want the tiles and I am able to wait as the house is not ready for them (I just ordered early to take advantage of the offer).

Any help appreciated

Thanks
Edward