Disastrous service from BMW Boksburg.

Took my car for service on the 8th Dec17, had a breakdown within 140km of driving it. Towed the car back to the dealer, was told it had Engine Freeze due to no oil. When I asked how that could be possible coz to my knowledge oil had to be changed as part of the service. Jackie called to rudely inform me that my quote for a new engine is R133000,00. Called BMWsa spoke to Mpho who advised that the dealer should deal with the mess, I was offered a loan car till the deal got a resolution. As I didn't understand how could I drive in with my car for service and after service it had an engine freeze. On Monday 15Jan18, received a call from the manager(Marius Van Vuuren) who advised that there's a slug in the engine, to my knowledge there should've been evidence of the slug while draining the old oil, & it would've been drained out had the service been conducted properly. Now I'm told that the loan car has a buyer & should be returned ASAP yet my car is not fixed, & was told that an amount of R5000 exl Vat should be payable for stripping my engine & yet I didn't agree to that amount. I'm also being told that as of today 17thJan18, I will also be charged R280 per day for storage. Can Justice be done... All I want is my car in the same condition it was before the service. I'm drained and frustrated with this issue. My job requires a car, as I work shifts.