Some good advice already given here.
A profile with the name Anitamark0218 was also listed on the following page, profile also now gone in Wilton just outside Salisbury (SP2 postcode):
External Link/Members OnlyAdding +44 doesn't necessarily mean much, I've done it myself.
And on the other foot, if someone was being closely controlled, the last thing the controller would want to do is give them the means to contact other people by voice or text. Or call the police themselves. So it may be innocent.
But the bottom line is if you have strong enough suspicions, or just feel that something isn't quite "right", listen to your experience.
The anti-trafficking units rely on tip offs as one of their information sources as it's challenging to get information on people traffickers.
Better someone pokes their head around the door to check in that everything's OK and be a false alarm (which they do with some inner city establishments anyway), than let someone get away with using another human being through threat or force.