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You should use the call+SMS filter
to be able to block calls and SMS from certain mobile numbers and prevent them from reaching your phone.
As for your question, not sure why you would do an Amber update with lumia Black since the Lumia Black update is the next update that was released after the Amber update. Specifically, the updates were as follows: Amber, Black, Cyan, Denim... whose letters are A, B, C, D. In line with this, you could choose to update your L1020 to the latest OS and firmware versions. Head to Settings > phone update and check for updates. Depending on your location, you should be able to install either the Cyan update or the Denim update. If you're connected to Wi-Fi, any available updates should start downloading.
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