It’s not all bliss these days at the posh Avon Salon and Spa in Trump Tower, where eyebrow guru Eliza Petrescu and the owners of the spa have become arch-rivals. Petrescu, who occupies a full floor in the salon and is booked a year in advance, filed suit against Avon, complaining that it failed to properly promote her product line. But she chose to remain at the spa, fearing that if she left, she might be liable for breaching her contract, which doesn’t expire until next February. Now, Petrescu says, not only isn’t Avon promoting her products, but it has discontinued some of them and is even copying them for its own line. “I put eyebrows on the map,’’ she insists. “The only attraction at the spa is Eliza, and apart from me the business is really down. So, they started charging clients for a cappuccino, at what is supposed to be a five-star spa, and they have replaced the fresh flowers with fake ones. It’s crazy.’’ An Avon spokesperson says, “Of course the coffee is free. The florals are from a world-renowned designer. The lawsuit filed by Eliza against Avon is simply an individual contract dispute, and it is company policy not to comment on pending litigation.” Next: Kenneth Cole Gets Kinky