Toby: I actually have a season ticket to cover my journey but I
wondered if I was being charged extra for coming in and out of the
same Oyster barriers.

MIG: So are you saying for specific stations you don't get penalised
for entering and leaving the same barriers but for others you would?

Route which hopefully has no charge: Ealing Broadway FGW to Burnham
(no Oyster) Come back to Ealing Broadway and exit barriers.

Route which might have a charge: West Kensington Ealing Broadway
(don't touch Oyster tower on arrival) FGW to Burnham Arrive back
at Ealing Broadway but don't only use Oyster when exiting West
Kensington.