Afiliated Sites

Since when have we been penalised to use Affiliated sites? We stayed at Invernahavon on 2/9.According to the Sites supplement the fee for M/H & 2 adults would be £18-30. The owner insisted on £20 charge.When pointed out the book fees he blamed the club entirely for the position and insisted on £20. Will the club reimburse me? Will think very carefully before using an AS site again.