Utc module battery

[carl123]

Hi' I have 2 x Breitling Utc modules that are about due for battery replacement, as was last done over 5 years ago at Breitling uk. It was about £120 each !
So am now keen to do myself , as don't get them wet and to be honest don't really wear, just admire them.
However I cannot remove case backs, have tried all methods on internet to no avail, I appreciate its a special tool with 11 sides and 19 mm but cannot find one anywhere, so i am reaching out to this wonderful community for any advice where to purchase
Very very grateful for any help.
Cheers.