Joint Membership - but only one outfit per site

My son and I have a joint membership - his m/home adorns my drive behind my little one.   I shall be 82 next month, I /we do not want to share, but I was not happy that I was charged as a non-member when we both spent two nights on the same Club Site.   Had I gone alone Mon/Tues and he had gone Thurs/Fri (for eg.) I would be £20 better off.   At my age, most of my contempories either go on a cruise or drop dead.   A bit of company - even to keep an eye on the old lady - would be nice without feeling ripped off.   The CC Insurance won't look at me - too old - so no benefits there.   The CC site in question had several empty pitches, having just coughed up my sub. - I was not a happy bunny (or squirrel come to that).