I have made two return journeys on M6 Toll recently. It was quite some time ago I used it previously and now, they don’t issue a receipt at the toll booth. To get a receipt, and see how much they charge, you have to go online. I would advise anyone using this road to do just that, for one leg of each of my two trips recently, the automatic system read my number plate as belonging to a car and charged me accordingly - that five pounds more than for a bike!
To get a refund you have to contact their customer services, not a particularly rapid experience!
Be warned!!