Hi Poucecku64
Thank you for your request.
You can upgrade from a monthly GA travelcard to an annual GA travelcard at any time. To do this, I recommend that you call us on 0848 44 66 88 (CHF 0.08/min) or +41 51 225 78 56 from abroad and give us your customer number. You pay by credit card.
You ca also go to a staffed ticket counter, where we accept all means of payment.
I wish you a nice day.
Kind regards
NicolasK