@alllo , alllo , Look in the charge port and blow/pick out(carefully) any dust/debri that may be causing an issue also look in the port for any bent pins and straighten very carefully with a tooth pick. If port is found to be bad/loose/damaged , this is really not a repair for the inexperienced because the charge port for your device is soldered to the mother board and the heat generated could cause further damage if not very careful. I will post a link to a tear down guide to get you inside the BlackBerry Curve 8530 to check the charge port and will also post a link showing what is involved in repairing a mini USB attached to the board(not your device, but shows how), if confident give it a go. The last link is to new charge port, which you can also do a search for better pricing perhaps if needed. If not wanting to do the repair yourself have a good computer/cell phone repair shop have a look and estimate repair. Good luck.
I hope this helped you out, if so let me know by pressing the helpful button.
[guide|5766]
https://www.youtube.com/watch?v=rTim6FIJPz8
http://www.ebay.com/gds/How-to-Fix-a-BlackBerry-Curve-Charger-Port-/10000000205273254/g.html
http://www.ebay.ca/itm/2-pcs-Micro-USB-Charging-Port-BLACKBERRY-Curve-8520-8530-Connector-Dock-Socket-/131795146019?hash=item1eaf9a5523:g:lz8AAOSw-tNXIZD0