We try to regularly move heavy items just that little bit and thus move the dents around. Each time we simply pluck the pile up, sometimes repeatedly over a period of some days, using any convenient (but not sharp) item. A knitting needle, kebab skewer or whatever are all useful and have been used. We find that after a fairly short time the patch has recovered - this is all on a woollen carpet with an underlay, synthetics may develop a longer lasting "set". The underlay appears to recover also, although we have not lifted the carpet to look.