Unreliable company

I ordered a computer chair which was indicated as "in stock" on the website, paid and acknowledged as "payment received". 8 days later, I am advised that the chair is out of stock, replenishment date is unknown and that they want to sell me another more expensive one for which I must pay more... Naturally, no answer on the telephone... "Send an e-mail as we are under lockdown..." Now to get a refund.... Looking at the reviews I should have looked here before ordering from them... My mistake...