Bajaj Auto — changing part is taking more than a month

Address:

400064

I son has given his bike on 05th Nov and they gave a slip saying you will get the bike by 30th Nov, today when we went to see the status of bike to our surprise they have not even started the replacement of part. Service centre say they don’t have parts available. Also Our bike is kept in very bad condition it’s not even 6 months old but looks lik 5 yrs old bike.
My son is very disappointed and feeling sad about if t.