BMW Locking mechanism

Well I lost the one (fob) key of my BMW 320i (F30) and the key that I have became faulty and I was told by the dealer that the locking mechanism on my car is faulty not the fob key. The dealer told me it would be R22600 to replace the locking mechanism. I do not have that kind of money with me at the moment and my car is still under factory warranty. Now BMW told me that hey won’t pay because they gave me a spare key 4 years back when I bought the vehicle brand new and I am not human and can never loose something therefore they wont pay. They would have paid if I had the spare key. It is only human to loose things at times and I can’t see how they won’t pay under my maintenance plan.

I am prepared to say under oath that I truly lost the key.

I am deeply disappointed with BMW and would never buy or recommend a friend to buy a car from them. absolutely poor and pathetic