Allowing arrears to build during contract, having to do manual meter readings every month, them taking no notice of those meter readings. Them trying to make huge increases in direct debit payments without authorisation, attempting to block transferring to a different supplier, not sending a final bill until 18 months later, then claiming they have been chasing me for it for all that time before referring the 'debt' (more than 18 months old, which is not allowed to even be billed under OFGEM rules) to a debt collector, and sending threatening emails to that effect. These guys are utter cowboys. Avoid at all costs.