Hi Prahoge62
Thank you for your request.
If you wish to cancel your Modular Travelcard within the period of validity and hand it in, you can obtain a refund from any staffed public transport point of sale or by phoning the SBB Contact Center on 0848 44 66 88 (CHF 0.08/min.) or if you are calling from abroad on +41 51 225 78 56. The refund amount is calculated as a percentage based on the number of unused days. A deductible is also charged.
You can find all the information here.
I wish you a good weekend.
Kind regards
NicolasK