Theft & non-existent customer service for 7 months

Lufthansa gave us the wrong seat -- and charged us for it. We had paid extra for a better seat but were given a different seat to the one we had booked, plus the new seat was broken! This was for an overnight international flight, for an elderly lady. We emailed a complaint through to their Customer Relations back in October (2017) -- but we are STILL waiting for a response (3 May 2018). Absolutely awful all-round experience that continues for SEVEN MONTHS.