Even after this sometimes it does not work. I did contact the customer care and they just told me that it was simply not possible and therefore I waited for either the transaction to get rejected or either for it to have like 40 confirmations but then again it's good if you have time and don't really care about the current price.
RBF need to be marked (as ON) when you broadcast your transaction first time.
Both RBF and CPFP would work if you use non-custodial wallets. If you use custodial wallets or exchange wallets, it is you bad choice at start and if services reject to support you, you can not blame on them.