That look like a poorly-informed report, since it seems to confuse 'premium rate' calls with 'local' (lo-call) rates and 'national' rates.
For example, it states: The DWP has already said it would phase out the use of 0845 numbers". 0845 numbers are charged at the 'local' rate (which was withdrawn for 'normal' calls some time ago). So (from a BT landline, as well as from some other providers) they're cheaper than normal calls.
Similarly, '0870' numbers are charged at the 'national' rate, which is usually no different to a 'normal' (geographic) number.