I feel for the OP a bit, crazy figures aside although if they don’t match his invoice and the customer has overpaid then the honest route of letting them know maybe advisable.
But im not fully sure I grasp the opening gambit of this thread fully so if £225 is the proper amount (allowing for maths issues), then the OP should be happy. I realise those that work for clean cabs and frilly pelmets may be shocked at this amount but sure its not unheard of and the OP is an employee of his own ltd company and can maybe pay a bonus at the end of the year to cover himself, just guessin.
Oh one thing for the OP though, one of the rules of truck club is not to boast about earnings unless its to while away a few hours at an RDC to wind agency folk up.
As he is new the other big rule is not to disclose to colleagues the whereabouts of the layby one has disposed of some ehhh carpet rapped evidence as the buggers tend to dig them up and try and take the credit.