Contract ended 31/01 - new provider from 01/08 - massive bill received for next month

[#1]

My contract with Plusnet ended on the 31/01. I used the switchover service for the first time and had my fibre broadband connected via Toob on the 01/08 in the morning. I did use Plusnet for 2-3 hours whilst waiting for the work to be completed.
Received a bill form Plusnet on the 01/08 with the following message: "We'll soon be taking a payment of £61.19 for your service. This will leave your account on or after 8th August 2025."
I'm thinking of stopping the payment (rather than asking for a reversal of payment under the DD protection), as I rather pay later than having to fight for what is a significant amount back.
Long shot but has nyone had a similar experience? I feel a call is the most appropriate way to go about it but... waiting times are a killer. Will try again in the morning though.
Thanks in advance.

[#2]

@ft01  I have a feeling you do not mean your account ended on the 31st January, 31st of July perhaps? Your bill on the 1st August will be for your next month with Plusnet so at the increased out of contract price. The billing system did not know you were leaving. I would not try and stop the payment, it will lead to more problems. let the bill be paid and it will be refunded in your final bill which will be around 3 weeks after your Plusnet service ceases.

[#3]

Ack & sigh. Indeed 31/07 (July). Note to self: proofread everything before you post not matter how stressed or tired you are.

Thank you for the advice. I haven't changed any of my utility providers for quite some time, lost touch.