Ecotricity gave away our promised John Lewis voucher

During switching we were told we’d be given £50, only to find it had been donated to the Green partyMy husband started the process of switching energy supplies to Ecotricity, but held off until we were free from our First Utility contract. Ecotricity emailed to say that if he continued with the switch he would receive a £50 John Lewis voucher. I completed the process when we were free of First Utility (I have a different email to my husband). When our first bill came in, at twi