The customer gets the value of the first clean so yes lose a job won't be great but you've done say the £100 first clean so won't lose out like. Still gotta sort out t&cs of this offer to cover myself. My say the customer gets the credit after 3 months or something or I may even just let the customer use the credit only on add on work - so they would get £100 credit for example towards a con roof clean, insides etc ....