My mother in laws MKC 2015 has a problem that it wont unlock with fob. then you use key and alarm sounds. wont start with fob in the backup slot eather. Been towed to dealer several times with them unable to find whats wrong. Replaced battery in fobs and car. Did it again! We are at wits end and at 78 she doesnt trust it anymore to drive. Afraid of getting stranded, again!