Telus messed up

Telus corporate store switched me from Business account to Consumer and told me they have added my credit card as pre-authorized payment, but found out there was no credit card added and a payment was missed. Been a customer of Telus for more than 10 years and never missed a single payment. Telus, through escalation all the way to account manager told me I am responsible for late payment even though mistake was by corporate rep, so Telus won't remove the late payment from credit report which dropped by 140 points. So going to cancel all mobility and home services, such a shame since I liked Telus and advocated for them.