Hi,
If the car had a defect that the pre sales inspection should reasonably have identified, the warranty company might expect the selling dealership to stand the cost of repairs, particularly within the first month/ first 1000 miles of ownership because the Das Welt warranty company expects that dealerships will undertake "robust" pre sales inspections.
Regardless, none of the issues you list are for you to pay for. That's why you paid a premium for a Das Welt approved used VW. If it was me, I would put my concerns in writing to the selling DP, the selling Sales Manager and the selling dealership's Service Manager to ensure that all of your bases are covered from the earliest possible time.
Even if you think "if something later fails, it will be covered under warranty", if you can actually articulate/ document the concerns now and they say "that's nothing to worry about, everything's fine" and then said concern becomes a reality within your warranty period and/ or otherwise within a reasonable period of time, you can then produce your documentation and they will not be in a defendable position should they expect you to pay for anything related. For example should someone later say that the warranty does not cover the issue.
To be asked to pay £150 etc up front as a security/ potential excess bond "just in case" is not something I've ever been asked to do with any dealership and if they're prepared to treat you like that 1 week into your ownership experience of a sizeable issue and inconvenience to you, how might they treat you "after a reasonable period of wear and tear use sir" (although is this a request from a dealership not affiliated to your selling dealership)?
I would be polite but clear and more formal with them (the selling dealership) on all issues that you have, both real and realistic potential issues. This would mean emailed concerns from me and me requesting emailed direct responses from them within 2 working days, for example, so that I could have a clear audit trail.
Regardless of their exchange policies, in the UK you are protected by the Sale of Goods Act which states that the car (used or otherwise) should be fit for purpose and free of minor defect within the first 6 months. You say you don't want to do so but you should always keep in mind that *you can* take steps to reject the car and seek a refund if they do not competently repair the car making it fit for purpose with minimum inconvenience to you and within a reasonable period of time.
Your experience to date, particularly the unsavoury £150 etc request would undermine my trust and confidence in the "customer focus" of the selling dealership, if the selling dealership had a hand in the £150 request.
Your car sounds very nice and hopefully this is all just a mechanical blip and/ or a communication breakdown/ different policies between dealerships.
Having bought a 2010MY GTi from Lookers VW within the last month, the car has had some major remedial work done and is actually going back in for some minor re-work this week but nothing has been too much trouble for them to date and they have offered a courtesy car each time with free insurance and with no "insurance excess money up front" requests; and to be honest, I would expect nothing less having committed a lot of money to the purchase.
All the best with it all.