Sorry to hear your sad news Brenbo.
Being a fellow sciatica sufferer on and off for the past (nearly) 40 years or so - initially caused by a sporting injury, I feel your pain; no pun intended. I’ve experienced the numb legs and feet, shooting sharp pains in the lower back, muscle spasms and the inability to stand up from a sitting position, and having to go up and down the stairs on my backside! Stepping heavily off a high pavement while on holiday in New Zealand a few years ago set it off again, and that’s not good when you’re on a driving holiday and can’t sit in a car. The 26 hour flight home was painful experience! I get periodic recurrences, and this year it’s given me quite a lot of grief; I wanted/needed to machine polish my car, but haven’t been able to, as using the DA isn’t the best therapy for back problems!
Makes you realise how much you take good mobility for granted when you become a sciatica sufferer.
Back on the subject of the service plan; if you’re still unable to drive to the dealer’s in a month’s time, another option might be to get someone you trust (friend or relative) to take your car to the dealer for the second service. It shouldn’t be too expensive to get them added to your insurance for a day.