It's very important we have our bitcoin wallet private keys. Not every wallet provider offers this. With your private keys, you can always choose to import your fund to any wallet and recover your fund, should anything happens to your present wallet.
Imtoken is a popular Ethereum ERC20 wallet service provider which is available in android and IOS version respectively for downloads. They have a version 2.0 which support bitcoin segwit address and you equally have access to the bitcoin private keys otherwise known as Mnemonic phrase in Imtotoken, some time ago when, when I couldn't adjust my bitcoin fee in the imtoken wallet of the IOS version, because they had upgraded off the auto fee settings, I reported the issue to them, and they promise to fix it. I opened a thread for it here:
https://bitcointalksearch.org/topic/m.51031268. In a bid to bypass their expensive fees, I imported my imtoken bitcoin wallet to blockchain .com and Mycelium wallets respectively, even though it showed successful importation, but my bitcoin balance never showed up in my new wallet. I raised the alarm and they replied to me they were going to work on it to be compatible with other wallets. It was at this point it dawn on me that I was not in control of my fund. Should anything happen to Imtoken bitcoin wallet. I had to quickly transfer off my bitcoin to other better wallet provider regardless of the fee incurred from Imtoken.
Other of my friends complained about the same experience and they have all move their fund away to a better wallet.
As I report this shady activities of Imtoken team, I can't tell if they have now work on their loophole.
We must check to ensure we are always successful in importing our bitcoin wallet to avoid loss of fund when such service providers stop functioning. I want to hear your thought about this.