Paying for Swiss travel pass

That is a little confusing. You are U.K. subjects (citizens, whatever) residing in Australia, right? As long as your credit card company knows the transaction is coming from you, it should be fine. That is usually, for me, a USA citizen residing in the USA, a matter of calling my credit card company and giving them a simple heads up to expect the transaction.
You can buy when you arrive in Switzerland, or buy through an agency, or buy on-line.

Thank you Sam for your speedy reply, Yes we are residents of OZ but English, so I will inform the bank. cheers.
One other question the quote we did online with Rick Steves rail Europe site would this be in US dollars or Australian $
do you know? Cheers Viv

The Rick Steves website is aimed at Americans. Prices are in US dollars.

Telviv, this should be no problem, I do it all the time. Your citizenship is irrelevant. Using a British credit card in Switzerland (or anywhere else in Europe) does not require notifying the company in advance, but it doesn't do any harm. I recently received a letter from my Credit card company that I needed to notify them for use outside Europe, but that is a new requirement.

But, why are you buying a Swiss rail ticket from "Rick Steves rail Europe"? That is a US seller, that is why they are pricing in US$. In this case your credit card transaction would take place in the USA, not Switzerland. I would cut out the middle man, remove any risk of mark-ups and buy directly from Swiss railways.
Webpage for Swiss passes here: http://www.sbb.ch/en/leisure-holidays/holidays--short-breaks-in-switzerland/swisstravelsystem/swiss-travel-pass.html
The price for 15 consecutive days is: CHF 440 2nd class, CHF 704 1st class.
I see no reduction for seniors. I would also say 2nd class is perfectly adequate. 1st class gets you 50% bigger seats, but no other advantages.

Thank you Chris F for information. I think you are right, we are looking at the Swiss pass & think that is the way to go.
Thanks for the info also on the bank card we have not had problems before just this once booking hotel in Chur but will ring the bank anyway just to check.
Cheers Viv

Just wondering Chris F, if we get 2nd class Swiss Pass, can we still upgrade & reserve for certain stretches such as golden pass Luzerne to Montreux and the Chocolate train pay the extra for reserving the "Vintage carriage" or do we have to book 1st class, to get the good seats on these trains ?Most grateful for your help. Cheers Viv

I was just looking at the Chocolate Train site this morning and it was 59 CHF for people with 1st class passes and 69 CHF for people with 2nd class passes.

For any paper ticket or rail pass, RS sales links allow delivery to USA street addresses only. Swiss consecutive-day passes can now be e-ticketed, and therefore the shopping cart may be less picky about your location, but I haven't tested that. A middle-man that's officially meant for your region is raileurope-world.com. The Swiss link or buying at a train station there should also be easy. There is no senior discount. We think 2nd class service is fine.

Thank you all for your input, we have now booked our 2country euro pass that worked out for us cheaper. We also contacted the bank who were just doing their job & looking after our account in case of fraud, which is rife. 😟