eslHQ - level of stress

You're confusing stress and intonation, and also the meaning of primary and secondary stress.

a) Primary and secondary stress refers to individual words - or rather the syllables in that word. Every word which is a lexical (rather than grammatical) item has one syllable that carries primary stress (marked here by bold type and underlining) - eg call, garden necessary. But if the word has 3 syllables or more, another syllable may have secondary stress - ie it's stressed but not quite as strongly as the syllable with the primary stress (marked here by underlining only) : necessary, estimate, alphabet

b) Intonation is a matter of a change in pitch direction. Utterances are divided into tone groups (indicated by //), and each tone group will contain one syllable which is not only stressed but also carries pitch change - in English mainly a rise, a fall, a rise then fall or fall then rise. In general, yes, it is usually the last stressed syllable which carries the pitch change (marked here by Italics) -
//Hello//My name's Pietro//but you can call me Peter//

But stress and intonation always depend on context. Look at your sentence again in a different context. A mother with her 8 year old child is talking to a teacher.

Mother - //Can we call you Peter//
Teacher - /You // can call me Peter// but your child // should call me Mister Mandercroft//

or

A - //Can I call you Peter//
B - //You can call me Peter if you want //but my name's Benjamin really//

And in the case of contrastive stress, even grammatical items can carry both stress and pitch change

A : //Why did you say // he isn't reliable //
b: //I said he is reliable// not that he isn't//