This is the last email I got from them:
I would like to take a moment and fully explain the situation once again.We realize that the situation has been stressful and we extend our deepest apologies for the hassle you have been through.
Bitdefender, like most reputable antivirus solutions incorporates a mechanism that blocks modifications to its files. This mechanism is in place so that malware cannot modify, remove, or corrupt its files. Without this protection it would be very easy to simply disable Bitdefender before infecting the device.
In a normal situation Bitdefender would simply disable this protection at uninstall, however, in your case, due to a malfunction, this mechanism has remained active. The steps to remove it are quite simple, and all they require is a reboot in recovery mode, where nothing except Apple system programs can run and therefore there is no risk of a malware infection. While in recovery mode a couple of files have to be deleted. This operation takes around 10 minutes tops, and all its steps are outlined in the article below:
https://www.bitdefender.com/consumer/support/answer/10131/I do understand why you've lost faith in Bitdefender and choose to go with a technician's help. The reason I am giving you all this info is to make sure you don't get swindled and be requested to pay hundreds of dollars for a 10 minute job.
As previously mentioned in our correspondence, a Bitdefender technician can remove the product free of charge and we can also issue the refund if this is what you decide.
Have a lovely weekend!
Best regards,
Alina Bizga
Bitdefender Support Team