Faulty Phone and no loan phone

I have a contract with Telekom, my device is still on warranty and the device battery is faulty, took it back to them, they told me they need to book the phone in, I will take 21 working days, I asked for a loan phone and they refused, all they can give is my Sim card and advised to buy another phone and still pay for my contract phone, how do I buy another phone and also if I don't, I should stay 21 days without a phone and still pay for my phone