When it comes to renewing your tax disc for your car you can now, if you have an electronic MOT, do it over the phone. The Government kindly set up a "semi-premium rate" for doing this. I call it "semi-premium rate" because it is an 0870 number which means you get charged at the national rate for the call which can be anything up to 10p per minute, unlike 0845 which is local rate.
Since the Government set up this number, 0870 8504444, it has generated revenue for the Government of £454,535.46. Of course, you could just ring 01792 782341, choose Option 2, then Option 3, and then ask to renew your tax disc. If you have a good deal on national calls from your provider (which most people nowadays have) you won't pay the Government's extra tax for renewing your road tax.