Reverso Duetto classic needs help!!

Hi,

I bought a Reverso Duetto classique for my wife last week. But we've got a problem with winding. Perhaps someone here could help us.

My wife tried to wind the watch to its fullest, but it didn't seem to reach its end. The boutique salesperson said to just wind till there is no clicking sound, and yes we tried and assumed it'd reached its maximum.

However, the watch slows down by a minute every 2 days even though we wind it everyday following the salesperson's instruction. Do you think the watch is defective? Thanks.

Regards,

Dan