Previous supplier claims they don't have meter reading

Despite receiving a manically happy email from Bulb on 16 August confirming that we had made the switch successfully, I received this email from my previous supplier Tonik this morning:
"We know you moved your energy supply but we’re emailing to let you know we’re unable to close your account as we haven’t received your final readings from your new supplier.
Please can you call them and ask them to send these to us as soon as possible so we can finalise your account and send you your final statement.
Many thanks
Member Services Team "
They asked me to phone you but I can’t see a phone number anywhere on the Bulb website, or any way of asking a question apart from this semi-public discussion group.
What must I do?

Despite receiving a manically happy email from Bulb on 16 August confirming that we had made the switch successfully, I received this email from my previous supplier Tonik this morning: "We know you moved your energy supply but we’re emailing to let you know we’re unable to close your account as we haven’t received your final readings from your new supplier. Please can you call them and ask them to send these to us as soon as possible so we can finalise your account and send you your final statement. Many thanks Member Services Team " They asked me to phone you but I can't see a phone number anywhere on the Bulb website, or any way of asking a question apart from this semi-public discussion group. What must I do?

Bulb Contact deatisl are the bottom of this page: https://help.bulb.co.uk/hc/en-us

Great, thank you – I had looked at a dozen different screens but couldn’t find that