SIXT Rental Car Tire Debacle & Unexplained €700 Charge

I rented a car from the SIXT company in Portugal. The vehicle's tire burst on the highway. When I looked, I found a massive cylindrical hole in the tire. I believe it's a tire seal. I assume the tire was previously mended, and this tire seal came out of it while driving. As a result, I heard today that the tire had been completely replaced, and 700 Euros had been charged. I'd appreciate specific details on why the tire was totally changed. When I returned the vehicle, the tire was in repairable condition. When I delivered the vehicle, there was no tear in the tire. I believe the rim damaged the tire during loading and unloading from the tow vehicle, rendering it inoperable. Rental Agreement 9504156870 for FIAT 500X [BB-69-BP]. I demand that the incident be investigated immediately.