you should move your number to a more reputable provider.

Except there is no reputable provider. In the absence of liability to compensate for the externality that the cost of security is borne by the phone company and the cost of the breach borne by the customer, the executivs make the rational decision to prioritize their bonuses over security. The same goes for tha banks that use grossly insecure phone-based authentication instead of more expensive methods. If a law established using such is gross negligence and thus the banks were liable for any losses incurred, you can bet this would change overnight. In the US, you have the option to use a Google Voice number. As Google absolutely refuses to hire humans for customer service, there are no humans to social-engineer, or store employees to suborn. Sadly, it's not an option in the UK.