Don't contact anyone online for spell casting. Waste of money, they could also be after personal information. Save the grief, study and do it yourself, it's not that hard.
I've never cast a spell to bring an old flame back, but you would need to overpower their free will. After this, you would need to work on the relationship so when the spell wares off [it will] the ex doesn't run away again. Remember though things end, sometimes it's best.