Switch rejected due to non-existent other switch in progress

petc

I'm trying to switch my gas and electricity supplier but the new supplier has rejected the gas switch on the grounds that there is already a switch in progress and I need to wait 21 days for this to complete before trying to switch again. This is completely false, there is no other switch in place. I asked them to explain but they just stated the exact same thing again.

I think I'm best to cancel the switch altogether especially based on the non-helpful emails from the new supplier, it's not a good first impression and I don't want them taking over the electricity then I have 2 separate companies on the go.

I'm also waiting on a reply from my current supplier about it but has anyone heard of this happening in error before?