Has anybody has success in booking different class for different segment using free companion voucher over phone. When i search online with redeeming companion voucher option it doesn't show options with different class for different segment but if I choose partner airlines it shows few BA only options with different classes with different segment. Can i book such flight with free companion voucher if i call?

Also, Does free voucher work only for one way and round-trip or does it work for multi-city? I would like to return from a different city because that has better availability? Will they book it as a single ticket with companion voucher if i call?

Thanks in advance.