An interesting discussion point raised by Ian from HKG.
Had much the same experience myself last Summer with BA LHR-PEK and CA PEK-ULN. The tickets were bought separately but I checked the BA website that they had interlining with Air China. On this basis, I obtained only a single entry visa for China (for our stopover on the way back from Mongolia). Imagine my consternation at T5 when the BA check-in told me that they would not/could not check my bags through to Ulaanbataar on Air China because they were separate tickets and CA were not a One World carrier – so there was no automatic interlining.
The prospect of using up my single entry visa at Beijing Capital just so that I could check-in my bag for ULN was inducing palpitations. Thankfully, I recalled that Senior Management had also recently travelled via PEK and had been able to exit the airport between flights… Unknown to BA’s information system, the Chinese issue 24-hour transit visas at PEK (can anyone imagine that happening at any UK port of entry?!) and there was no problem. Otherwise, the prospect of having to go through the entire visa application process in Ulaanbataar all over again was a genuinely grim prospect.
Yes, everyone is now trying to do their best to avoid taking liability for other people’s costs but there are times when service providers ought to be in the business of solving problems for their customers, not adding to them.