I understand your frustration, Jan, but please bear in mind that this is a function of vtech and their poor quality poorly supported products. If you'd like a recommendation for a better quality phone system that would be better supported and which has parts available, I can recommend some options for you.
I am an independent technician and I've spent my personal time, unpaid, in an effort to assist with the question for which you solicited my services. This site works on the honor system, and to that end, I have prioritized working with you ahead of other paying customers.
Although you’ve already paid your fee to the site, I am only compensated for my efforts when customers such as yourself leave positive feedback for my work. I apologize this is not the outcome you had hoped for, though this is really beyond either of our control. I do hope you’ll consider leaving a 5 star rating for me, rather than “shoot the messenger”, so that I may get credit for my time spent in good faith to answer your question accurately. Rating 1 or 2, or not rating at all, does not produce a refund, it only penalizes me for trying to help 0 that would be blaming me for the poor quality of the vtech product, jeopardizing my livelihood, and tarnishing my professional reputation because of vtech.