The neutral phrase for this phenomenon is language contact which is one of the ways in which language change can occur.
What you have reported in your question is a matter of (having a wrong) perspective. I used to dislike the seemingly vast amount of loanwords, so I can understand those that don't like it, but I changed my mind. Consider this: you're living now, so your perspective comes from what is happening now. You (a general you) learned a certain language that you call Italian since your childhood, with a specific vocabulary. During your life you've experienced an acquisition of foreign terms, so from your perspective it's been "contaminated" (for lack of a better word) by other languages.
However this is a false perspective because the "base language" you learned as Italian is not "pure" at all. It's the result of all the previous influences and borrowings; there is no such thing as truly, 100% pure language. There are more welcoming and less welcoming languages, so to speak, but you won't find a truly immutable, pure language, at least not in the Information Age we're in. Geographically isolated languages might show a higher degree of "purity", but they can still be influenced, because that's the very nature of languages.
Going back to my previous statement, the Italian you learned is full of borrowed words that you think are perfectly Italian. Just to name a few:
- Gazzella (gazelle), comes from Arabic ghazāl
- Cifra (digit, number), comes from Arabic ṣifr
- Bistecca comes from beef steak
- Manichino comes from fr. mannequin
- Fiordo, comes from Norwegian fjord
- Grattacielo is a calque from English skyscraper
There's even cliccare, a verb formed by attaching the verb ending -are to the root clic, from English to click.
English has acquired many terms from Italian as well: opera, stanza, pianissimo, a cappella, falsetto, but I could really go on. It's also not a coincidence that these terms are all related music and theatre. Italian has been the Lingua Franca in Europe in the past, such as during the Renaissance, and many terms are still used in present day.
It should be mentioned that many loanwords stay side by side with the local terms, such as is the case with those that are used in defined contexts: The English term corner is used in soccer matches only, as far as Italian is concerned, while the corresponding word angolo is used for all instances (including soccer too at will).
In conclusion: languages change, and one of the ways they do is to assimilate foreign terms. That's just what they do. Trying to "save" a language can be good when the native speakers are dying out, but in this case it's kind of pointless.