The main reason for buying bags from the brands I do is they have excellent aftercare. I also think it encourages a brand to make great products from the start as they won't want the bag coming back.
It's also a good reason to buy bags from leatherwear specialists who do fashion and not fashion houses who do leather wear.
Gucci to Gucci
Totally wonderful, dedicated team. They have done everything from a 'quick extra stitch' to replacing an exact belt-strap on a 30+ years reversible belt.
BV to BV
They couldn't do anything about the rubbed surface of my lamb skin hobo (my fault) but they do stand by their products. Thanks for reminding me I should take my coat to be cleaned

.
Hermes to Hermes
Happy to restore my 60 yo bag to look like new (only better). I have heard some not-so-good repairs too though.
I've never tried Chanel, it was policy to repair and recondition but I am not sure they do so much anymore.
I clean and polish my 'stuff' about twice a year but never use 'protective' sprays except on suede and nubuck.
WARNING TO ALL WHO BUY THE ABOVE PRE-LOVED.
IF 'WORK' HAS BEEN DONE ON YOUR GUCCI/HERMES/BV BAG (I am sure it's the same with LV and Chanel) unofficially or DIY including waterproofing, dyeing, re-stitching etc WORK WILL NOT BE DONE ON YOUR BAG.
I took a Trussardi canvas shopper with crocodile-trim to my local dry cleaners. It
really needed cleaning and I could not have carried the way it was however they didn't take care of the trim (all it needed was some covering in silver foil). Still, many dry cleaners in the UK will not even 'have a go' with bags and nor will shoe repairers so it
is really important to only buy the best from the best otherwise it could literally cost me thousands with a bag I can't use.