LONDON, March 23 (Reuters) - Credit Suisse (CSGN.S) bondholders are seeking legal advice after the Swiss regulator ordered 16 billion Swiss francs ($17.5 billion) of Additional Tier-1 (AT1) debt to be wiped out under its rescue takeover by UBS (UBSG.S). Not only did bondholders expect protection, but UBS is paying $3.23 billion to Credit Suisse shareholders. One Paris-based manager of a debt fund that held Credit Suisse AT1s said he had been "spammed" with emails from lawyers. Facing any challenge could be Credit Suisse, its new owner UBS, Swiss regulator FINMA or the Swiss government. It also cited an emergency March 19 ordinance which it said authorised FINMA to instruct Credit Suisse to write off the bonds.

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