SP, it sounds like you had a square taper style bottom bracket (the bearings and spindle mounted in the bike that the crank arms bolt on to), and now have a spline style bottom bracket. As the others have mentioned, either should last a long time if properly installed and tightened. Unfortunately, you have to depend on the bike mechanic to do this properly, and finding a good bike shop near you can be hard. If you don't mind posting your area, we might be able to suggest some places; Yelp can be a good resource, too.
In any case, once you get the current BB and cranks repaired or replaced, I'd *strongly* suggest taking the bike in for a checkup periodically (within a couple of weeks initially, and maybe every 6 months after that) so that a bike mechanic can look over the bike and make sure the crankarm bolts are still tight, the BB is secure, and so forth. Bikes are not a fix and forget type of item; they've got bearings and lots of moving parts, and need periodic maintenance.