HMRC, as should all companies, solely using premium rate telephone numbers for telephone access, be made to provide access by telephone numbers starting with either 01 or 02, the STD codes for the UK, depending on where they are in the UK.
I always, where a telephone number is 08…. except of course 0800 (Free telephone code), check to see if they have an International number, if they do I substitute 0 for the +44, the UK International code. In most cases this will convert the number to the standard STD code telephone number. Our own GP used to have an 08 number, but due to complaints and comments from registered patients they have now changed to an 01 number.
Do not put up with a bad or indifferent service, everyone should register their complaints on a formal basis. Also, why not invoice the organisation for the cost of the call, especially when you have waited and the only answer was an automated voice and you are waiting in an ever ending queue, hoping a human voice will eventually make contact. So much of your time wasted.
Take charge of the situation, by not doing so bad service is allowed to continue.