If you'd bought using a credit card you might've earned points that periodically are converted into cash credited to your account. Applies to high-value purchases (or most).
When I rang my debit card provider to warn I was about to spend £23K on a new kitchen (I saved for 7 years), the customer assistant advised (unofficially) that I buy using my credit card in order to get the points. I pay the credit card off in full each month so it didn't matter to me whether I used a credit card or a debit card, and it didn't bother the card provider which card I used. Eventually, via converted points I received the equivalent of a month's food. So I did the same when I bought a new car, gained ditto amount of "return", though my car wasn't an RS5 just a humble estate car.
Even if you buy helped by a loan you'd still get points = cash (or vouchers depending how your card provider does it) if you buy with a credit card and swap funds between accounts.
I doubt you'd be allowed to buy a house (or the difference between simultaneously selling & buying) using a credit card. But if you buy a brand new house there are payments to the developer when you choose colours, styles, fittings and finishes, unless you opt for the basic ones included (no one does, as they work it so you won't want the horrible basic options). These extras mount up (my parents did this, it's too easy to do), so you could gain a lot of credit card points there.
